Shock absorber



Patented Oct. 24, 1950 SHOCK ABSORBER ,Edwin F. Rossman, Dayton, Ohio assignor to General Motors Corporation, Detroit, Mich., a

corporation of Delaware 7 Application J uly 8, 1947, Serial No. 759,586

3 Claims. (01. 188 -88) This invention relates to improvements in hydraulic shock absorber.

It is among the objects of the present invention to provide a hydraulic shock absorber with means for increasing the restriction to fluid flow therein as the piston approaches the end of its travel in one direction, thereby substantially preventing bottoming or striking the closure .member at one end of the cylinder with damaging effect.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig.1 is a broken, longitudinal sectional view of the shock absorber equipped with the present invention. 7

Fig. 2 is a fragmentary view of the section shown in Fig. l, the piston, however, being shown in a different position with the cylinder.

Referring to the drawings the numeral 26 designates the working cylinder of the shock absorber. At one end it has portion of a head member 2| telescopically fitted into the cylinder, this head member having a central opening in which the piston rod 22 is slidably supported. A larger diameter portion of the head member 2l'is exteriorly threaded to be received by the threaded end of a tube 23 which surrounds the cylinder 2| and forms an annular chamber therebetween hereinafter referred to as reservoir 24. The outer end surface of the head member 2| is recessed to receivethe packing assembly 25 having a member which sealing'engages'the piston rod 22 to permit its reciprocation through the packing gland. A locking ring 26 is also threaded into the end of the tube 23, engaging the head member 2| and locking it securely in position in the tube. The end of the rod 22 extends to the exterior of the shock absorber and has a disc 21 attached thereto and a mounting ring 28, this mounting ring providing the means for attaching the piston rod to one of the relatively movable members whose movement the shock absorber is adapted to control. Another tube 29 has its one end fitting about the disc 21 and is secured thereto in any suitable man ner preferably by Welding, this tube 29 forming a stone guard which surrounds the tube 23 substantially for a greater portion of its length when the shock absorber is collapsed as shown in Fig. l. Ducts 30'are provided in the head member connecting the recess containing the packing gland assembly 25 and the interior of the reservoir 24, these ducts returning any liquid to the reservoir that might leak from the cylinder along the bearing in the head member supporting the piston rod 22.

The endof tube 23 opposite the head member 2| has a cup-shaped, closure member 40 secured thereto preferably by welding. This cup shaped closure member 40 has spaced inner ribs 4| for purposes to be described. A mounting ring 42- is secured to the closure member 40 and provides means for securing this end of the shock absorber to the second relatively movable member whose action the shock absorber is adapted to control.

A valve cage 45 has a portion telescopically received by the end of the cylinder 20 opposite the head member 2|. This valve cage 45 rests upon the spaced ribs 4| of the closure member 40. Valve cage 45 has a central opening 46 surrounded by a ridge 41 on the side of the valve cage within the cylinder 20, this ridge 4'! forming an annular seat upon which the valve 48 is normally yieldably urged by a ring secured in the valve cage and having inwardly extending resilient fingers 49 engaging valve 48. The peripheral surface of the valve cage 45 within the confines of the cylinder 20 has an annular groove 50. Another annular groove 5| is provided in the surface of the valve cage which rests upon the closure member 140. A plurality of ducts 52 extend between the annular grooves 50 and 5| providing communication therebetween. A valve 53, consisting of one or more ring shaped resilient discs, has the annular inner edge thereof secured to the valve cage in such a manner that the ring disc or discs are biased urging the outer peripheral portion against an annular valve seat 54 formed on the valve cage 45. Thus the opening 46 in the valve cage is normally closed by the spring loaded valve 48 engaging the cylinder side of the valve cage while the annular groove 5| on the opposite side of the valve cage is normally closed by the valve 53.

The cylinder 20 has a plurality of annular rows of openings arranged in a circular'row in the annular wall of said cylinder. Openings B0 are at the end of the cylinder 20 engaging the valve cage 45, these openings communicating with the annular groove 50 provided in the valve cage 45. Another row of openings 6| are in the wall of the cylinder 20 just above the inner edge of the valve cage 45. Still another circumferential row of openings 62 are in the wall of the cylinder but are arranged a predetermined difi".

ings 62, BI and 60 and thus communication between the openings 62 and 6! in the cylinder and the annular groove 50, ducts 52 and annular groove in the valve cage 45.

A piston 80 is secured to the piston rod 22, this piston having a plurality of fluid passages, one

group '12 arranged in an inner circular row while another group 13 :are'arranged in an :outer surrounding circle. Passages "l2 arenormally closed by aspring loaded valve '14 while passages 73 are normally closed by a spring loaded valve 15. Valve 14 is operative to establish restricted flows of fluid through the piston passages '12 as'thepiston is moved upwardlyiin the cylinder toward the head member 2|, while valve 'li'zis adapted to establish a substantially unrestricted flow of fluid through the passages 13 in the piston inresponse to the movement of the pistontoward the valve cage member 45.

Fig. 1 shows the shock absorber in fully collapsedposition while Fig. 2 shows the shock absorber in an extended position iii-which the piston 80 has the openings 62 in the cylinder fully uncovered. When the piston is moved toward the valve cage 45, by approaching movements of the relatively movable members between which the shock absorber is secured, the piston exerts pressure upon the fluid within the lower working chamber designated by the numeral 50, said fluid pressure moving the valve l5 from its seat to establish a substantially unrestricted flow of fluid from chamber 90 into the chamber'tl within the cylinder 20. Due to the presence of the piston rod '22 in chamber 9|, all fluid displaced from chamber 95 cannot enter chamber "9% and consequently the fluid displaced by the'piston l'0d'22 in the chamber 9| will-be discharged through the openings 52 and 6! in the cylinder wall'through the annular passagelZ, ducts '52 to the annular groove 5! in the valveca-ge, this fluidpressure actuating the valve 53 to establish -a restricted flow of fluid 'from'the working chamber 96 into the reservoir 23. Continued movement of the piston 80 in the direction toward the'valve cage will eventually cover opening't'l after which fluid displaced by the pistonrod-Z'Z in the chamber 9| 'will be forced throughthe substantially reduced openings or orificesfil in'the' cylinder wall, thereby greatly restricting the fluid flow from chamber 90 and consequently resisting'to an increased degree the movement'of the said piston 85 toward the valve cage :5. 'All fluid flow through the annular passage 12, established either'by the combined openings 62 and El or the opening 5! alone is directed against the valve 52 which restricts the fluid flow'from the ducts 52 of the valve cage. From thisit may be seen that the movement of the shock absorber piston-80; after closing openings 62 in the cylinder, is increasedly resisted. Thus the piston as it approaches the end of itstravel toward the valve cage 45 will be highly resisted thereby preventing bottoming or more particularly the striking of the piston upon the valve cage with damaging effect.

As the piston moves away from the valve cage 45 upon the separating movements of the relatively movable members between which it is connected, it exerts pressure upon the fluid within the chamber'fil thereby actuating valve 14 to establish a restricted flow of fluid from chamber 9| through the piston passages 12 into the cylinder chamber 90. The fluid displaced from chamber 9! into chamber is insufficient to fill said chamber, consequently, the valve 48 will be lifted to establish a substantially unrestricted fluid flow from the reservoir 24 through the opening 46 in the valve cage into the chamber 90 completely to fill it as the piston continues in its movement away from the valve cage 45.

From the aforegoing, it will be seen that the present invention provides for a simple construction by means of which restriction to the fluid flow of the shoe absorber is increased as the piston approaches the end of its travel towardthe valve cage member v 35 thereby substantially pre-' venting bottomingor more particularly the striking of the valve cage member by the piston with damaging effect.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A hydraulic shock absorber comprising a cylinder closed at one end, the other end communicating with a fluid reservoir; a valve-cage fitted into said other end of a cylinder, said cylinder having small openings in its wall adjacent the valve cage and larger openings in said wall more remote from said valve cage; a central opening in the valve cage, surrounded by a ridge on the cylinder side of the cage, said ridge providing a valve seat; a valve yieldably urged upon said seat; radial ducts in the valve cage, each duct terminating in an annular groove in the peripheral' surface of the cage fitting within the cylinder and in the surface of the cage exposed tothe fluid reservoir; a resilient disc valve urged against said surface ofthe valve cage, normally to close. the ducts; notches in'the cylinder end communicating with .the annular groove in the valve cage; means cooperating with the cylinder and valve cage to provide a passage connecting the notches in the cylinder with the openings in the wall thereof; and a valved piston in the cylinder adapted to cover the larger openings therein during a certain range of movement of the piston in the cylinder.

2. A hydraulic shock absorber comprising a cylinder; a piston in said cylinder; a fluid reservoir in communication with one end of the cylinder; a valve cage fitting into said one end of the cylinder and having a valved passage opera-.- tive to permit fluid to flow from the reservoir into the cylinder; an annular groove in the peripheral surface of the valve cage surrounded by the cylinder and in the surface of the valve cage exposed to the reservoir, said grooves being in communication with-each other by ducts inthe valve cage; a valve on the valve-rcagebiased to cover the annular groove exposed to'the reservoir, and operative to permit a restricted flow therefrom into the reservoir; a plurality of orifices in the cylinder wall, certain of which open into the cylinder'and others'into the annular groove in the peripheral surface of the valve cage, certainof the orifices opening into the cylinder being constantly open and the others covered by the piston during a portion of its travel in the cylinder; and means surrounding the cylinder and valve cage, providing a connecting passage between all of the orifices in the cylinder wall.

3. A hydraulic shock absorber comprising a piston containing cylinder closed at one end; a fiuid reservoir surrounding the cylinder; a fluid flow control device in the other end of the cylinder, said device consisting of a cage member having two, oppositely acting valves, one of which is operative to effect a flow of fluid from the reservoir into the cylinder as the piston moves away fromsaid cage, said cylinder having a plurality of holes operative as long as the piston does not cover them, to effect fluid flow from the cylinder as the piston moves toward said cage, said cylinder having other holes more adjacent the cage, said other holes restricting fluid flow from the cylinder to a greater degree than the 6 holes more remote from said cage; and means fitting about the cylinder and cooperating therewith to provide a passage connecting all of said holes with the second valve of the fluid flow control device.

EDWIN F. ROSSMAN;

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 982,008 Knapp Jan. 17, 1911 1,658,962 Aikens Feb. 14, 1928 2,025,199 Funston Dec. 24, 1935 2,036,623 Focht Apr. 7, 1936 2,138,513 Rossman et a1 Nov. 29, 1938 2,199,880 Elliott May 7, 1940 2,324,058 Boor et a1 July 13, 1943 2,327,295 Whisler 1- Aug. 17, 1943 2,332,161 McIntyre et a1 Oct. 19, 1943 

